N-substituted perfluoroalkanesulfonamides are broadly described in U.S. Pat. No. 3,639,474 as active herbicides and plant growth modifiers. 5-Acetamido-2methyltrifluoromethanesulfonanilide and 5-acetamido-2-chlorotrifluoromethanesulfonanilide were particularly disclosed therein to have particular plant growth modifying activity, i.e. as to their ability to retard the growth of grass without significant distortion of the normal foliar shape. This plant growth modifying activity is of interest because it reduces the number of times grass must be mowed.
It has now been found that a novel derivative of trifluoromethanesulfonanilide, 5-acetamido-2,4-dimethyltrifluoromethanesulfonanilide, is a much more effective grass growth regulator than 5-acetamido-2-methyltrifluoromethanesulfonanilide, the preferred compound of the above mentioned patent. It has been found, both in greenhouse testing and in outdoor testing, that the compounds of the present invention can be used at greatly reduced rates of application. This result is both unexpected and economically desirable.
The invention also includes horticulturally acceptable salts of 5-acetamido-2,4-dimethyltrifluoromethanesulfonanilide, novel intermediates useful for its preparation and processes for the preparation thereof.